Vagus nerve stimulation reduces ventricular arrhythmias and increases ventricular electrical stability.

BACKGROUND: Transcutaneous stimulation of the auricular branch of the vagus nerve (AB-VNS) is a potentially noninvasive, inexpensive, and safe approach for vagus nerve stimulation that suppresses the induction and duration of atrial fibrillation and reduces sympathetic nerve outflow in healthy humans. Researchers have not determined whether AB-VNS affects ventricular arrhythmias. OBJECTIVE: To evaluate the antiarrhythmic effects of noninvasive AB-VNS on ventricular arrhythmias induced by myocardial infarction (MI). METHODS AND RESULTS: Twelve beagle dogs were randomly divided into the following two groups: a AB-VNS group (coronary artery occlusion and noninvasive AB-VNS) and a control group (coronary artery occlusion but without AB-VNS). We examined spontaneous ventricular arrhythmias, ventricular electrophysiological properties, and cardiac function in conscious dogs. Morphology, fibrosis, and ultrastructures were also assessed. AB-VNS significantly reduced the occurrence of spontaneous ventricular arrhythmias, including isolated premature ventricular complexes, ventricular couplets, ventricular bigeminy, ventricular trigeminy, and ventricular tachycardia. AB-VNS effectively increased ventricular electrical stability, including significantly prolonged ventricular effective refractory periods, decreased the dispersion of effective refractory period, enhanced the ventricular fibrillation threshold, and decreased the maximum slope of the monophasic action potential duration restitution curve. AB-VNS treatments alleviate ventricular interstitial fibrosis after MI. However, cardiac function was not improved, and MI-induced ultrastructural changes in the myocardium were not reversed by 4 weeks of AB-VNS. In addition, AB-VNS for 4 weeks resulted in mild mitochondrial swelling within the neuronal axons of the auricular vagus fiber. CONCLUSIONS: Noninvasive AB-VNS reduces the occurrence of spontaneous ventricular arrhythmias in conscious dogs with MI. AB-VNS increases ventricular electrical stability and alleviates ventricular interstitial fibrosis induced by MI.

Association of VKORC1 gene -1639G/A polymorphism with atrial fibrillation in ethnic Uygurs and Hans from Xinjiang / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the association of VKORC1 gene -1639G/A polymorphism with atrial fibrillation (AF) in ethnic Uygurs and Hans from Xinjiang.</p><p><b>METHODS</b>The above polymorphism was detected among 100 Uygur and 102 Han AF patients and 103 Uygur and 111 Han subjects that have no AF with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.</p><p><b>RESULTS</b>A statistically significant difference was detected between the patient and control groups of Uygur origin in terms of genotypic and allelic frequencies (P<0.05). Logistic regression analysis also indicated the -1639G/A polymorphism as an independent risk factor for AF in Uygur population (OR=2.085, 95% CI: 1.067-4.072, P=0.031). No similar statistical difference was found between the patient and control groups of Han origin (P>0.05).</p><p><b>CONCLUSION</b>The -1639G/A polymorphism of VKORC1 gene is associated with AF in the Uygur population but not in Hans.</p>

Relationship between new-onset atrial fibrillation and sympathetic neural remodeling in a canine acute myocardial infarction model / 中华心血管病杂志

<p><b>OBJECTIVE</b>To establish the canine model of new-onset atrial fibrillation (AF) after acute myocardial infarction (AMI), and explore the relationship between new-onset AF and sympathetic neural remodeling in this model.</p><p><b>METHODS</b>Twenty four adult mongrel dogs were randomly divided into 4 groups by applying random number table. Group A (n=6): ligate the left circumflex artery (LCX). Group B (n=6): ligate the LCX and right atrial anterior artery and right atrial middle artery. Group C (n=6): ligate left anterior descending artery.Group D (n=6): sham operation.Sequential electrophysiology study was performed in all dogs to determine the AF induction rate, AF duration, effective refractory period (ERP), the density of tyrosine hydroxylase (TH) and norepinephrine transporter (NET) before AMI or sham operation, and at 30 min, 2 hours and 4 hours after AMI or sham operation.</p><p><b>RESULTS</b>(1) The highest AF induction rate of right atrium and left auricle was 96.7%(58/60) and 95.0%(57/60) in group B, 81.7%(49/60) and 38.3%(23/60) in group A, 28.3%(17/60) and 35.0%(21/60) in group C, 20.0%(12/60) and 33.3%(20/60) in group D. (2) At 4 hours after AMI, AF duration was significantly prolonged in group B(193.50±54.67) s, compared with group A(53.83±9.37) s, group C(45.00±19.50) s, and group D(16.67±4.50) s (all P<0.05). (3) In group B, the ERP of AF was prolonged at 30 minutes after AMI and shortened at 2 hours and 4 hours after AMI compared with baseline level(all P<0.05). (4) The TH density of left atrium ((3 485±694) µm2/mm2) and left auricle((2 645±454) µm2/mm2) in group A and the TH density of left atrium ((7 873±1159) µm2/mm2) and left auricle((3 070±605) µm2/mm2) in group B were significantly higher than those in group C ((1 474±475) µm2/mm2, (1 177±277) µm2/mm2) and group D ((678±206) µm2/mm2, (489±125) µm2/mm2) (all P<0.05), and the TH density of right atrium and right auricle in group B were higher than group A (all P<0.05). The NET density of left atrium((476±75) µm2/mm2) and left auricle ((414±52) µm2/mm2) in group A and the NET density of left atrium((527±81) µm2/mm2) and left auricle((429±85) µm2/mm2) in group B were lower than that in group C ((1 044±105) µm2/mm2, (867±67) µm2/mm2) and group D ((1 438±60) µm2/mm2, (1 027±119) µm2/mm2) (all P<0.05).</p><p><b>CONCLUSIONS</b>Ligating the LCX, right atrial anterior artery and right atrial middle artery at the same time can significantly increase the success rate in establishing the canine model of new-onset atrial fibrillation after acute myocardial infarction and can also increase the AF duration.Cardiac sympathetic remodeling after acute myocardial infarction is associated with induction and duration of AF.</p>

Comparative Case Analysis of Atrial Fibrillation in Patients With Han, Uygur, Kazak and Hui Ethnic Groups in Urumqi City / 中国循环杂志

Objective: To comparatively study the atrial ifbrillation (AF) in patients with Han, Uygur, Kazak and Hui ethnic groups in Urumqi city. Methods: A total of 1510 AF patients treated in 12 hospitals in Urumqi city from 2008-01 to 2012-12 were retrospectively studied. There were 1310 patients enrolled in our research including the 4 ethnic groups of Han, n=995 (75.95%), Uygur, n=168 (12.82%), Kazak, n=55 (4.20%) and Hui, n=92 (7.02%). Results: ①The gender ratios were similar in 4 ethnic groups, P>0.05, while the AF type, cardiac function and risk factors were different, all P0.05, while the blood routine test, biochemistry and cardiac ultrasound examination were different, all P Conclusion: The AF patients were different in AF type, biochemistry, cardiac ultrasound and function, anti-coagulation treatment among 4 ethnic groups of Han, Uygur, Kazak and Hui in Urumqi city.